undo

verb

un·​do ˌən-ˈdü 

ˈən-

undid ˌən-ˈdid 

ˈən-

; undone ˌən-ˈdən 

ˈən-

; undoing ˌən-ˈdü-iŋ 

ˈən-

transitive verb

1

: to open or loose by releasing a fastening

2

: to make of no effect or as if not done : make null : reverse

3

a

: to ruin the worldly means, reputation, or hopes of

a politician undone by scandal

b

: to disturb the composure of : upset

she's come undone

c

: seduce sense 3

intransitive verb

: to come open or apart

undoer

ˌən-ˈdü-ər 

ˈən-

noun

Synonyms

• demoralize
• emasculate
• paralyze
• unman
• unnerve
• unstring

Examples of undo in a Sentence

You can't undo the past.

The damage cannot be undone.

He was undone by greed.

Recent Examples on the Web

Electoral victories can be undone, regulations weakened or eliminated entirely. —Aissa Dearing, JSTOR Daily, 4 Nov. 2024

Remember that some things can be done or said, but they cannot be undone. —Meghan Rose, Glamour, 1 Nov. 2024

Trump’s plan is to undo that progress, throw billions of dollars of clean energy investment out the window and give other countries the economic opportunity, instead. —Bill Weir, CNN, 1 Nov. 2024

Furthering Fair Housing rule that required HUD and states, counties and cities to pursue meaningful action to undo decades of housing discrimination. —Marcus Baram, USA TODAY, 31 Oct. 2024

Word History

First Known Use

before the 12th century, in the meaning defined at transitive sense 1

Kids Definition

undo

verb

un·​do ˌən-ˈdü 

ˈən-

undid -ˈdid  ; undone -ˈdən  ; undoing -ˈdü-iŋ 

1

: to make or become unfastened or loosened : open, untie

undo a knot

2

: to destroy the effect of : nullify, reverse

3

a

: to cause the ruin of

your stubbornness undid you

undone by greed

b

: to disturb the calmness of : upset

she's come undone

undoer noun